1. Field of the Invention
The present invention relates to an apparatus and method for electronically tracking and detecting facial features and apparatus and methods for automatic speech recognition.
2. Description of the Related Art
There are many circumstances where it would be desirable to electronically analyze an individual's facial features. For example, automatic speech recognition devices, access control systems, electronic storage and retrieval systems for personal profiles and medical/dental screening systems could make use of such analysis techniques. Speech recognition systems which utilize analyses of facial features may find wide application in noisy environments where it is difficult to utilize acoustic speech recognition alone, e.g., in a military aircraft or in a factory. The problem, however, has been the lack of an effective means for accurately translating an individual's facial features into useful electronic data. This is particularly problematic where the individual is continually changing facial orientation with respect to the detection equipment.
There are two primary approaches to electronically detecting facial features. The first approach involves mechanically mounting an apparatus to the individual's face. One example of this approach is a system being developed at the Massachusetts Institute of Technology which requires attaching physical sensors or strain gauges to face. U.S. Pat. No. 3,192,321, a variation on the theme of face-mounted detectors, describes placing a cup-shaped detector over an individual's mouth. In the detector, there are several point sources of light and photo resistors which monitor lip movements. The pattern of detected lip movements is compared with a previously recorded pattern so as to recognize speech. Because the detectors of these systems are manually attached to the individual's face, they cannot properly be characterized as an electronic tracking system. This approach merely provides a detection system.
A second approach involves projecting a grid of light onto an individual's face and detecting the extent to which the grid is distorted by the contours and features of the individual's face. Such an approach is described in J. Herron et al., "Biomedical Imaging Processing For Dental Facial Abnormalities", Proceedings For The International Conference On Cybernetics And Society, Washington D.C., IEEE Systems Man & Cybernetics Society, Sept. 19-21, 1977 at pages 462-464; and U.S. Pat. No. 4,449,189. This approach may be used for detecting facial features.
Neither of the above approaches is particularly versatile. For example, it would not be practical to incorporate one of these systems in a speech recognition system to caption automatically a television news broadcast. Requiring that the newscaster either have his mouth covered with a face mounted detector or be lighted with light stripes would be highly intrusive. Thus, where intrusiveness has precluded the prior art systems, electronic speech recognition had been forced to rely on acoustic recognition devices which are of limited accuracy.
Accordingly, it is an object of the present invention to provide a more versatile system for electronically tracking and detecting facial features.
It is yet another object of the present invention to provide a system for analyzing facial features to provide information from the detected features.
It is a further object of the present invention to incorporate such a system into a speech recognition apparatus.
Other objects, features and advantages of this invention will be apparent to those skilled in the art of pattern analysis and recognition from the problems which this invention solves, and from the following summary, drawings and detailed description of the invention and its preferred embodiment.